The complete mitochondrial genome ofDiadegma semiclausum(Hymenoptera: Ichneumonidae) indicates extensive independent evolutionary events

Abstract

Few complete mitochondrial genomes representing limited families in the order Hymenoptera have been sequenced. Here, we sequenced the complete mitochondrial genome of Diadegma semiclausum (Hymenoptera: Ichneumonidae). This genome is 18 728 bp long, the second largest hexapod mitochondrial genome sequenced in its entirety and that with the highest A+T content at 87.4%. Four tRNAs are rearranged compared with the ancestral arrangement. Gene rearrangement mechanisms are different among all three rearranged regions. Six tRNAs have a large variable loop, which is not found in other metazoan mitochondrial genomes. trnS(AGY) uses the abnormal anticodon TCT but trnK uses the normal CTT. The A+T-rich region is very long (2161 bp). An extremely A+T-rich (99.1%) 1515 bp tandem repeat region with three types of repeat elements is located between cox1 and cox2, and the most likely ancestral element originated from the 3' end of cox1. Independent tandem duplications followed by mutation-insertion-deletion is the best model to explain the formation of this region. These results indicate that independent evolutionary events occurred extensively, such as gene rearrangement events, gene rearrangement mechanisms, derivation of tRNA variable loops, and tandem repeat region evolutionary processes, all of which likely contribute to the diversified features of hymenopteran mitochondrial genomes.

The first mitochondrial genome for the wasp superfamily Platygastroidea: the egg parasitoidTrissolcus basalis

“…For each codon family, the sum of the A-and T-rich codons is close to the maximum possible RSCU value. Similar codon usage bias has been observed in other hymenopteran mt genomes Cha et al 2007;Wei et al 2009). …”

The complete mitochondrial genome of the leafminer Liriomyza sativae (Diptera: Agromyzidae): Great difference in the A+T-rich region compared to Liriomyza trifolii

“…The gene sizes and locations were normal as in other insects' mitogenomes. The secondary structures of lrRNA and srRNA accorded to the models proposed for these genes from other insects (Wei et al, 2009;Cameron and Whiting, 2008;Gillespie et al, 2006;Cannone et al, 2002). Fortynine helices were present in L. sativae lrRNA the same as in A. mellifera and L. trifolii (Gillespie et al, 2006;Wang et al, 2009), belonging to six domains (Fig.…”

Two nearly complete mitogenomes of wheat stem borers, Cephus pygmeus (L.) and Cephus sareptanus Dovnar-Zapolskij (Hymenoptera: Cephidae): An unusual elongation of rrnS gene

“…Cephus species share identical anticodon with most insects except for trnS1 (AGN) which uses UCU as an anticodon. This unusual anticodon has been suggested to be associated with gene rearrangements (Wei et al, 2009) and observed in some hymenopteran as well as other insect species (Cha et al, 2007;Lee et al, 2008).…”

“…The rrnS secondary structure is predicted for the first time in sawflies and includes 30 helices like most known hymenopteran species (Gillespie et al, 2006;Wei et al, 2009;Wu et al, 2014), but an exception was reported for braconid species (Wei et al, 2010b) (Fig. 4).…”

“…The precise ends of the rRNA genes were defined as being bounded by the adjacent tRNA genes (Dowton et al, 2009). The predicted secondary structures of rrnS and rrnL were constructed according to the commonly accepted comparative approach and algorithm-based methods proposed for other hymenopteran species (Wei et al, 2009(Wei et al, , 2010a. XRNA 1.1.12b (http://rna.…”